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#1
10-30-2011, 09:35 AM
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Random misfire 05 V6 chevy
MY 05 V6 Chevy pick up occasionally will have a misfire. This usually happens while I am driving thru large hills in Kansas with high winds. The check engine light will flash for a few minutes until I get off the hill and out of the wind. Next hill same thing until sometimes the engine shakes and will not lock up the torque convertor. I have tried 3 times to get this diagnosed with good mechanics with scanners. Last month I put on the ac delco cap and rotor wires and plugs and a coil for maintenance reasons. Truck is still doing the same thing only under very heavy load. I took the mechanic for a ride with scanner on the truck. I hit 5 grand rpm in first gear nothing took it to 4500 rpm and check engine lite flashed. Scanner shows random misfire 3 plug then goes off again it showed random misfire #2 plug then clears. He checked that o2 sensors are working properly cats seem to be Ok . He went thru a long line of tests for other problems and could find nothing like everyone else that has checked. With winter coming on and me having to drive thru the hills in Kansas this makes me nervous. At some points the next town could be 60 to 90 miles away and that wouldnt be a big town. Possibility of no wrecker or service in that town. Dont feel like sitting on the side of the hwy in Kansas in freezing weather waiting 3 hours for a $400 wrecker to come get me. Can anyone help? New fuel pump also.
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#2
10-30-2011, 06:11 PM
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is this a 4.3?
I had a similar problem on my 01 S10 while under warranty the dealer chased his tail trying to find it,finally replace a coil wire and it was fixed.
__________________
Everything comes and goes Pleasure moves on too early And trouble leaves too slow |
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#3
10-31-2011, 07:55 AM
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Yes this is a 4.3. But as said before coil and wires plugs and cap and rotor were replaced 3 weeks ago using dielectric grease. Same problem as before. The only thing I can add to this is this truck just doesnt get the mileage as my last 2 v6 trucks or seem to have as much power on take off. Best mpg on this one was 22 with a tail wind. My first and second would easily pull 24 and often 26 mpg on the hwy.
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#4
10-31-2011, 08:06 AM
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A fuel delivery problem can cause random missfire codes as well.
A few other things to consider: Fuel pressure, fuel filter, dirty/defective injector. Ever run any fuel injector cleaner in the tank? I use Lucas, it works excellent. These are just a few more suggestions, good luck. |
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#5
10-31-2011, 08:13 AM
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Fuel pump is delco about 3 months old filter built into fuel pump assembly. I use injector cleaner every month. I may get me a can of lucas
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#6
10-31-2011, 05:19 PM
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Tx:
This could be an intermittent MAF sensor failure, too. My tow vehicle ('02 2500HD, 8.1L) had exactly the same issues when towing that your vehicle has. Try tapping on the sensor with the engine running; if the engine stumbles then you've found your problem. You might be able to just clean it and have it work okay, but maybe not. If your mileage has always been bad, the sensor may never have worked correctly or been contaminated from day one. Hope this helps. Tom |
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#7
11-01-2011, 08:21 AM
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Yesterday I was going to take a run down to Waco so I stopped at auto zone and got the lucas fuel injection cleaner then filled up the truck. About 30 miles into the drive there was a wreck so I had to stop. I noticed the idle was up abut 50 rpm and it seemed a little smoother as well. Coming back from Waco the fuel economy looked better. Normally from a fill up to 3/4 tank I get about 140 miles. I got 162 miles on this tank. After getting home I took it out to the country road I use for testing. I hit 85mph in 2nd gear and no misfire. I tried it again and hit 87 mph no misfire. Sunday when I did this 4 out of 4 times it misfired at about 80mph.
I am not saying for sure that it is fixed but it sure looks like it. The final test will be when I go to Mo. and hit those Kansas hills with the wind and check my real mileage. I bought the Lucas deep clean fuel system cleaner for 9.97 as Poncho recommended. I went back and bought Lucas upper cylinder lubricant with fuel injection cleaner that treats 100 gallons for 9.97 also. I treated every car I have. I was buying the walmart brand fuel injection ckeaner before this but no more. Thanks Poncho for the Lucas advise and all others that made suggestions. |
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#8
11-01-2011, 01:31 PM
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Friend of mine has a '98 Toyota 4runner. Did the exact same thing. It was due for plugs and wires anyways and we changed the coil pack on the #3 cylinder that was having a random misfire. Continued to do the same thing, ended up having a bad fuel injector.
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#9
11-01-2011, 05:15 PM
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Tx:
Glad to hear it was that simple of a fix. Your luck seems to be way better than mine. I have noticed my HHR running kind of sluggish lately, so I think I will try the Lucas cleaner in that as well. Thanks to all the great people on this site like poncho, who care enough to spend time helping other folks! |
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#10
11-02-2011, 04:13 PM
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The 4.3 fuel injection system is very sensitive to fuel pressures. 1 PSI can cause what you are seeing. Has, or is it hard to start after sitting overnight? Does it feel like it has no power when you floor it from a stop? Does the misfire happen when the TCC is locked up and you start up a slight hill? All these can be caused by a fuel pump going bad, even though the fuel pressure looks good on the guage. I have been there with the 4.3, and grab your wallet tight when you see how much the fuel pump assy costs. Don't get a cheap one if this turns out to be the problem, get the GM pump or you will be changing it again sooner than you would like.
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Less said,,,,,,,, Less mended. |
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#11
11-03-2011, 08:49 AM
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No hard starting new ac delco fuel pump. The torque convertor is locked up but its a large hill and high winds and it shifts down into 3rd. Still running good yesterday . We had high winds but not many hills around my house.
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#12
11-05-2011, 01:51 PM
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look for cracked vacuum lines. They could wreak havock on everything from the map sensor to the mas airflow. if the truck is 4x4 check the vacuum lines underneath that go to the transfer case they are usually always brittle.
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#13
11-06-2011, 09:54 AM
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My first fill up 150 hwy 250 city came in at 19 mpg. The city mileage was with some pretty strong winds. I have tried 3 times to get it to misfire again but it hasnt yet. I did get the truck up to 90 in 2nd gear though not bad for a 6 banger
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#14
11-07-2011, 10:40 AM
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Just another fuel pressure item to consider. The fuel pressure regulator can give you the problem, and the misfires will be random.
Depending on how bad it is, you can experience hard starts when hot, hard starts when cold, low mileage and/or reduced power-particularly on hills. If the pressure is low, at all, I would change the regulator before changing the pump. I realize you may have the problem solved, just throwing this in the mix for others with problems.
__________________
Rich The real democratic American idea is, not that every man shall be on a level with every other man, but that every man shall have liberty to be what God made him, without hindrance. Henry Ward Beecher "The problem with socialism is that you eventually run out of other people's money." Margaret Thatcher |
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#15
11-22-2011, 08:54 AM
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Ok Made the trip to Mo. Not one misfire mileage was better going up but coming back I was running 75 and 80 mph but still pulled over 19 mph. That lucas fuel injecter cleaner is good stuff
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